1. Field of the Invention
This invention relates to a method of treating a secondary battery having at least one component containing alkali metal, e.g. lithium, and to apparatus for treatment of such a battery, in order to enable safe extraction and recovery of the alkali metal and optionally other components. In batteries, alkali metal may be present as the metal or in alloy form or as an intercalation compound, and the invention is applicable to all these forms.
2. Description of the Prior Art
A high energy density battery such as a lithium battery includes an active material of its negative electrode in the form of highly reactive alkali metal and an electrolytic solution containing LiPF.sub.6 or LiAsF.sub.6 which are reactive with water to produce HF. The battery typically further includes a positive electrode containing metal components capable of being regenerated. However, there has been not described any method of industrially processing spent batteries such as lithium batteries or any apparatus for processing such batteries.
The demand for high energy density batteries shows a yearly increase, and problems arise in terms of effective utilisation of chemical materials used in secondary batteries and of environmental pollution caused by batteries. For example, lithium and transition metal elements (Mn, Co) used in a lithium battery are valuable materials suitable to be regenerated. Moreover, a lithium secondary battery capable of being charged and discharged has been extensively used as a power supply for back-up of a computer or a power supply of small size domestic electric equipment, and is expected to be used for power storage or as a future power supply for an electric automobile. Accordingly, there must be developed a method of processing batteries and a method regenerating battery materials for suppressing environmental pollution due to chemical materials contained in the spent batteries and for effectively recovering such components used in batteries.
European patent application 94105151.8 (now published as EP-A-618633) and pending U.S. patent application Ser. No. 08/220,220 describe a process of treating a lithium battery by contacting the lithium in the battery with a liquid alcohol, to form an insoluble reaction product, followed by supply of liquid water and alcohol to form LiOH. The solution of LiOH in water and alcohol can then be withdrawn from the battery. The present invention takes a different approach to the problem.